• The relationship in women between mild hirsutism or acne to androgen levels has not been well-defined. We investigated this in 62 Caucasian women, aged 18 to 21 years, by relating these pilosebaceous signs to plasma free testosterone (fT), the main circulating determinant of plasma androgenicity. Women with mild hirsutism (n = 13) had a significantly elevated fT (12.7 ± 5.5, SD, pg/mL [44.1 ± 19.1 pmol/L]) compared to normal controls (7.4 ± 2.7 pg/mL [25.7 ± 9.4 pmol/L]), as did subjects with minor acne (10.7 ± 4.25 pg/mL [37.1 ± 14.7 pmol/L]). The most important finding was the striking variability in the relationship between pilosebaceous overactivity and fT levels. In mildly hirsute subjects plasma fT was normal in half of the subjects, and the coefficient of variation of plasma fT was about twice what one would expect from individual variability. We could not demonstrate correlations among the variables of hirsutism, acne, and plasma fT. On the other hand, among 15 women with modest elevations of plasma fT levels (up to twofold), 27% had moderate hirsutism, 40% had mild hirsutism, and 33% had none. However, four of five of the latter patients (without hirsutism) had acne. The relationship of fT to acne severity varied similarly. To define the interactions between androgens and the pilosebaceous apparatus, we propose a model in which variation in apparent skin sensitivity and the level of androgen seem to contribute about equally to the pathogenesis of mild hirsutism and acne. The clinician should suspect that hyperandrogenemia will be/found in about half the women with mild cases of hirsutism, and one third with minor acne.